Miller J
J Exp Psychol Hum Percept Perform. 1979 Aug;5(3):546-62.
These experiments investigate the influence of frequency of occurrence of a visual stimulus (stimulus probability) on encoding processes, in an attempt to discover what sorts of mechanisms allow cognitive processes to modify perceptual processes. Experiments 1 and 2 show that frequently occurring visual letters do not facilitate encoding of visually similar letters. This implies that stimulus probability does not directly affect the feature detectors used in encoding the letters. Four more experiments provide evidence that stimulus probability has its effect on the availability of an abstract code that is generated by the encoding process from the visual input. Results from the experiments with letter stimuli could be interpreted using a model similar to the logogen model of Morton. Experiments with nonsense forms suggest that subjects use abstract codes in dealing with the forms only when the stimuli are constructed from a set of orthogonal features. A secondary finding was that visual quality has an effect that extends past the feature analysis stage and into a stage in which the visual input activities an abstract code. This result calls into question the common practice of interpreting the interaction of a factor with visual quality as evidence that the factor affects visual feature analysis.
这些实验研究视觉刺激的出现频率（刺激概率）对编码过程的影响，试图发现何种机制能使认知过程改变感知过程。实验1和实验2表明，频繁出现的视觉字母无助于对视觉上相似字母的编码。这意味着刺激概率不会直接影响用于字母编码的特征探测器。另外四个实验提供了证据，表明刺激概率对由编码过程从视觉输入中生成的抽象代码的可用性产生影响。字母刺激实验的结果可以使用类似于莫顿的词素发生模型来解释。无意义图形实验表明，只有当刺激由一组正交特征构成时，受试者才会在处理图形时使用抽象代码。一个次要发现是，视觉质量的影响会延伸到特征分析阶段之后，进入视觉输入激活抽象代码的阶段。这一结果对将一个因素与视觉质量的相互作用解释为该因素影响视觉特征分析的常见做法提出了质疑。
